Block copolymers having silane compounds grafted to the polymer chain such as described in Japanese Patent Nos. JS-8132-032-A and JS-8225-103-A are known in the art. The grafted silane compounds improve internal adhesion of the block copolymers and adhesion to non-polar substrates. The silane-modified block copolymers are typically prepared by extruder grafting with a free radical initiator.
U.S. Pat. No. 4,320,214 describes a process for grafting silanes to ethylene-type resins including the addition of zinc oxide which stabilizes the product. The zinc oxide is added during melt-kneading of the polymer and is stated to not reduce the rate of graft formation.
U.S. patent application Ser. No. 835,090, filed Feb. 28, 1986, now U.S. Pat. No. 4,783,504, describes a sealant composition possessing good UV stability, good oxidative stability, and good adhesion. The sealant composition includes a silane functionalized polymer component which is prepared by reacting enough silane of the general formula R R'.sub.n SiY.sub.3-n (where n is 0, 1 or 2 and where R is a non-hydrolyzable organic group which is capable of grafting onto the polymer, R' is a non-hydrolyzable organic group incapable of grafting onto the polymer and Y is a hydrolyzable organic group) with a block polymer component to thereby functionalize the block polymer component and provide a resultant sealant composition with adhesion which is resistant to deterioration in the presence of water. The sealant composition may contain zinc oxide as a retardant which is added after the grafting reaction.